1. Field
The following description relates to an in-wheel actuator applicable to a vehicle, such as an electric automobile, which is driven with electrical power, and an in-wheel assembly comprising the same.
2. Description of the Related Art
Hybrid vehicles and electric vehicles have gained more popularity due to harmful environmental effects from air pollution and a shortage of fossil fuels. A hybrid vehicle uses an internal-combustion engine to generate power, and uses an electric motor as an auxiliary power source. An electric vehicle uses an electric motor as a main power source.
With the development of technologies for batteries and motors, it is expected that electric vehicles, known as pollution-free cars, will replace “transition” vehicles, such as hybrid cars, since electric vehicles emit no pollutants or carbon dioxide during driving.
An in-wheel system has a driving motor mounted on a wheel, and delivers power from the driving motor directly to the wheel. The application of the in-wheel system allows a vehicle to have a compact and organized driving system, thereby reducing vehicle weight and improving a degree of freedom in vehicle layout or design. In addition, the in-wheel system contributes to optimization of a vehicle frame to increase collision safety. Further, the in-wheel system increases a drive motor performance of the vehicle and facilitates a larger interior space by optimally balancing weight across the vehicle.
In addition, the size of a driving motor is proportional to a level of output torque. Therefore, the bigger the size of the driving motor is, the higher the output torque can be achieved. However, an in-wheel assembly of an in-wheel system needs to be designed such that a driving motor embedded in a wheel should not protrude outward to prevent the driving motor from any external force. In addition, a brake is embedded in the wheel of the in-wheel assembly and the driving motor is arranged in the wheel, separately from the brake. Therefore, there is a limit to increasing the size of the driving motor.
In order to achieve output torque high enough to drive a vehicle, a decelerator can be installed to an output shaft of a driving motor. In this case, the size of the driving motor may be reduced. However, a decelerator is usually arranged outside of the driving motor in series. Thus, the size of the in-wheel assembly, including the driving motor, is not reduced as much as expected.